sc4808b-1 Semtech Corporation, sc4808b-1 Datasheet

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... The dual outputs can be configured in Push-Pull, Half Bridge and Full Bridge format with programmable dead time between two outputs depending on the size of the timing components. The SC4808B-1 also features a turn on threshold of 4.4V and is available in MSOP-10 package. Typical Application Circuit Vin RSENSE ...

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... SC4808B ...

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... < SC4808B ...

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... Notes: (1) Only available in tape and reel packaging. A reel contains 2500 devices. (2) Lead free product. This product is fully WEEE and RoHS compliant. 4 SC4808B ° ° ...

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... TOT VCC: The supply input for the device. Once VCC has ex- ceeded the UVLO limit, the internal reference, oscillator, drivers and logic are powered up. A low ESR capacitance, should be used for decoupling right at the IC pin to mini- mize noise problems. 5 SC4808B-1 www.semtech.com ...

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... Bottom Mark xxxx xxxx yyww = Datecode (Example: 9912) xxxx = Semtech Lot # (Example: E901 xxxx 2006 Semtech Corp. CS Slope Comp. OVER CURRENT Peak Current Enable OSC 500mv SOFT START R SYNC SYNC 01-1) 6 SC4808B-1 Disable LUVLO R www.semtech.com OUTA OUTB GND ...

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... POWER MANAGEMENT SC4808B-1 Typical Characteristics (SC4808B-1A) 100.0 95.0 90.0 85.0 80.0 75.0 70.0 -40 -25 - (°C) Iq (start up) vs. Temperature 3.90 3.85 3.80 3.75 3.70 3.65 3.60 -40 -25 - (°C) Iq (operating) vs. Temperature 3.22 3.21 3.2 3.19 3.18 3.17 3.16 -40 -25 - (°C) Reference vs. Temperature 2006 Semtech Corp. 1.69 Start up Iq, Vcc = 4V 1.68 1.67 1.66 1.65 1.64 1.63 1.62 1.61 1. 110 125 -40 - Offset vs. Temperature ...

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... POWER MANAGEMENT SC4808B-1 Typical Characteristics (Cont.) 100 -40 -25 - (°C) Vcc UVLO Hysteresis vs. Temperature 3.170 3.165 3.160 3.155 3.150 3.145 3.140 3.135 3.130 3.125 3.120 -40 -25 - (°C) Line UVLO vs. Temperature 140 135 ...

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... POWER MANAGEMENT SC4808B-1 Typical Characteristics (Cont.) 180 170 160 150 140 130 120 110 100 90 80 -40 -25 - (°C) Soft Start Delay time vs. Temperature 2006 Semtech Corp. Soft Start Delay Time 110 125 9 SC4808B-1 www.semtech.com ...

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... PWM CONTROLLER SC4808B double ended PWM controller that can be used in voltage or current mode applications. The SC4808B-1 provides a 4.4V VCC UVLO, and a 3.125V ref- erence. The oscillator frequency is programmed by a resis- tor and a capacitor network connected to an external refer- ence provided by the SC4808B-1. The two outputs, OUTA and OUTB, are 180 degrees out of phase and run at half of the oscillator frequency ...

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... Application Information (Cont.) VCC UNDER VOLTAGE LOCK OUT Depending on the application and the voltages available, the SC4808B-1 (UVLO = 4.4V) can be used to provide the VCC undervoltage lock out function to ensure the convert- ers controlled start up. Before the VCC UVLO has been reached, the internal refer- ence, oscillator, OUTA/OUTB drivers, and logic are disabled ...

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... SYNC pin, the internal os- cillator frequency will be synchronized to the positive edge of the external control signal. SYNC is a positive edge trig- gered input with a threshold set to 1.0V (SC4808B-1 single controller operation, SYNC should be grounded or connected to an external synchronization clock within the SYNC frequency range (see page 3) ...

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... R33 OVER CURRENT Two levels of over current protection are provided by the SC4808B-1. The current information is sensed at the CS pin and compared to a peak current limit level of 525mV. If the 525mV limit is exceeded, the OUTA and OUTB pulse widths and duty cycle is reduced until the CS pin reaches a second threshold of 950mV. At that point, the OUTA and OUTB are disabled, and after a delay of 140µ ...

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... Note: After afew c ycles the perturbation disappears and stable operation returns Note: After afew c ycles the perturbation is still pres ent, although this w ill caus e jitter, but there is no instability Note: After afew c ycles the perturbation becomes larger, and causes instability. 14 SC4808B-1 www.semtech.com ...

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... One of the methods to alter the peak current information is to add a positive going ramp to the output of the current sensing circuitry. The SC4808B-1 achieves this by using an internal slope compensation circuit. The oscillator ramp is internally buff- ered and an internal 25kOhms resistor in conjunction with an external resistor at the CS pin will program the level of slope compensation ...

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... Sensed Mosfet current Sens Sum m ation of Isense and slope com pensation, at the CS pin of the SC4808 Sense Buffered Oscillator Ramp I CS 2006 Semtech Corp. Slope Compensation generation from Buffered Oscillator Ramp D>50% 16 SC4808B-1 Note: Below wave form s are not to scale. www.semtech.com ...

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... Stable current mode operation with Slope Compensation D>50% Note: After a few cycles the perturbation becomes larger, and causes instability. Note: After a few cycles the perturbation disappears and stable operation returns. 17 SC4808B-1 Error Signal from Error amplifier Error Signal from Error amplifier Error Signal from Error amplifier www.semtech.com ...

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... SC4808B-1 has an internal soft start circuit that limits the duty cycle for a duration approximated by the formula be- low. Also the soft start circuitry is activated if an over cur- rent condition occurs ...

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... Cout only, and connections between Cout and the load must be short, wide copper areas to minimize in- ductance and resistance. 5) The SC4808B-1 is best placed over a quiet ground plane area. Avoid pulse currents in the Cin FET loop flowing in this area. GND should be returned to the ground plane close to the package and close to the ground side of (one of) the VCC supply capacitor(s) ...

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... POWER MANAGEMENT Gain & Phase Margin 50 40 Phase -10 -20 -30 10 Typical SC4808B-1 Push Pull Converter Gain/Phase plot at Vin = 36V, Vout = 3.3V, Iout = 10A, Fosc = 650kHz 2006 Semtech Corp. Gain 100 1000 Freq (Hz) 20 SC4808B-1 225 Gain Phase (deg) 180 135 ...

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... POWER MANAGEMENT Gain & Phase Margin (Cont Phase -10 -20 -30 10 Typical SC4808B-1 Push Pull Converter Gain/Phase plot at Vin = 48V, Vout = 3.3V, Iout = 10A, Fosc = 650kHz 2006 Semtech Corp. Gain 100 1000 Freq (Hz) 21 SC4808B-1 225 Gain Phase (deg) 180 135 ...

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... POWER MANAGEMENT Gain & Phase Margin (Cont Phase -10 -20 -30 10 Typical SC4808B-1 Push Pull Converter Gain/Phase plot at Vin = 72V, Vout = 3.3V, Iout = 10A, Fosc = 650kHz 2006 Semtech Corp. Gain 100 1000 Freq (Hz) 22 SC4808B-1 225 Gain Phase (deg) 180 135 ...

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... POWER MANAGEMENT Typical Step Load Vout 500mV/Div Iout 5A/Div Cout = 6X22uF (132uF) Ceramic Typical SC4808B-1 Push Pull Converter Step Load plot at Vin = 48V, Vout = 3.3V, Step = 37% to 75% Iout, Fosc = 650kHz 2006 Semtech Corp. 100us/Div 23 SC4808B-1 www.semtech.com ...

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... POWER MANAGEMENT Evaluation Board Schematics 2006 Semtech Corp. 24 SC4808B-1 www.semtech.com ...

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... PA0500 P8208T PE-68386 SC4808 SC1301A SC4431 MOCD207 CBRHD-02 25 SC4808B-1 Foot Print CON\5OUTPUT_HALF_BRICK CON\3INPUT_HALF_BRICK SM/C_1206 SM/C_0805 SM/C_1210_GRM SM/C_2220 SM/C_0805 SM/C_1210_GRM SM/C_1206 SM/C_1206 SM/C_1210_GRM SM/C_0805 SM/C_1206 SM/C_0805 SM/C_0805 SM/C_0805 SM/C_0805 SM/C_0805 SM/C_0805 SM/C_0805 SM/C_0805 DIODE_D2PAK SOD123 SMB/DO214 SOD523 ...

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... POWER MANAGEMENT Evaluation Board Gerber Plots Board Layout Assembly Top Board Layout Top 2006 Semtech Corp. Board Layout Assembly Bottom Board Layout Bottom 26 SC4808B-1 www.semtech.com ...

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... POWER MANAGEMENT Evaluation Board Gerber Plots Board Layout INNER1 2006 Semtech Corp. Board Layout INNER2 27 SC4808B-1 www.semtech.com ...

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... SIDE VIEW -A- AND - DETERMINED AT DATUM PLANE -H- X DIM INCHES (.161) C (C) G .098 .020 X .011 Y .063 Y Z .224 P Semtech Corporation Power Management Products Division 200 Flynn Road, Camarillo, CA 93012 28 SC4808B-1 DIMENSIONS INCHES MILLIMETERS NOM MAX - - - .043 1. .006 0.00 0. .037 0.75 0. .011 0.17 0. .009 0.08 ...